Joint trowel



Oct. 2, 1962 J. c. HOVELAND JOINT TROWEL 2V Sheets-Sheet. 1

Filed Feb. 15, 1961 lNVE/VTOR JULIA N CLEON HOVEfLAND Oct. 2, 1962 J. c.HOVELAND 3,056,159

JOINT TROWEL Filed Feb. 13, 1961 2 Sheets-Sheet 2 lNVE/YTOR JULIAN CLEONHOVELAND itates atent ice 3,056,159 JOINT TROWEL Julian Cleon Hoveland,Edmonton, Alberta, Canada, assignor to M. D. Muttart, Edmonton, Alberta,Canada Filed Feb. 13, 196i, Ser. No. 88,808 2 Claims. (Cl. -43517) Thisinvention relates to trowels for smoothing out plastic materials ormastics over room or building joints and particularly corner joints.

In the building industry, the use of plaster on walls and ceilings hasto a great extent been replaced by a dry wall construction. Thisconsists of nailing up sheets of plaster board or the like to formwalls. This leaves the problem of filling the cracks or joints betweenthe sheets in the walls and at the corners. It is common practice tofill the joints with a mastic. An excess of the mastic is supplied atthe joint, and then a tape is pressed over the joint or into the cornerover the mastic. Prior to this invention, the application of the tapeand final finishing of a corner joint was mainly a hand operation. Asthe mastic acts as an adhesive for the tape, an excess of mastic must besupplied in order to be sure that the entire tape is firmly secured tothe wall over the corner. When the tape is firmly pressed into thecorner, mastic exudes from beneath the tape along the edges thereof.After the tape is firmly pressed into position, a layer of mastic issupplied to the outer surface thereof, and this is trowelled laterallyalong the joint to form an outer surface over said mastic which mergeswith the adjacent wall surface. This is a long and tedious task, andrequires skilled work ers. In addition, it is usually necessary to cleanup mastic from the walls near the corner.

The present trowel is particularly for corner joints, but it may beconstructed for wall joints, and in either case, it may be in two formsor it may be convertible into two forms. For the sake of convenience,the description will deal mainly with a corner trowel. This trowel is tobe used after the mastic has been inserted in the corner joint and thetape placed in the corner over the mastic. One form of this tool is thenused to press the tape firmly into the corner while confining the excessmastic pressed from beneath the tape to the corner area where it isneeded. In fact, this trowel directs the excess mastic back over theouter surface of the tape and presses it into the final form. If enoughmastic material has been applied in the first place, the one movement ofthe trowel over the tape may be sufficient to complete the job. The tooltrowels this mastic from the corner laterally to cause the outer surfaceof the finished mastic to merge with adjacent wall surfaces. On theother hand, it may be preferred not to apply sufficient mastic or theremay not be enough mastic for the whole job in the first place. In thiscase, either an alternative trowel is used, or the original trowel isconverted into a tool ready for the final operation. Additional masticis placed over the tape, and then the trowel is moved over said mastic.This action tapers the mastic laterally down to the outer surfaces ofthe walls, while leaving a suitable thickness of mastic over the tape.

'If desired, the tape may be pressed into the corner by hand or by someother tool, and the corner trowel referred to in the second stage of theabove operation may be used to flatten out and smooth the final coatingof mastic. Furthermore, the corner trowel is designed to fit accuratelyin a wall corner and to travel straight along said corner, therebyeliminating the necessity of having a specially trained operator.

A joint trowel according to the present invention comprises a plow whendesigned for a corner joint is formed with a substantially V-shapedouter working surface and has a longitudinal nose along the apex of theV. A pair of runners are provided along the working surface, one

on each side of and spaced laterally from the longitudinal nose. Theserunners have outer longitudinal surfaces starting at the working surfaceof the plow near one end thereof and sloping away from said surfacetowards the opposite end of the plow. As most corners are in the form ofa V, the V of the working surface of this plow usually is a littlegreater than 90 so that when inserted into a corner, the longitudinalnose is spaced from the bottom of the corner while the working surfaceof the plow spreads laterally from said nose to the adjacent walls. Inother words, the angle of the working surface is always a little largerthan the angle of the corner for which the tool is designed. The runnerskeep the forward end, with respect to the direction of movement of thetrowel, spaced upwardly from the Walls forming the corner, but thesloping surfaces of said runners permit the opposite end of the workingsurface at the outer edges thereof to engage the walls.

The tool described immediately above may be used alone for the finishingoperation. On the other hand, it may also be used for the tape-pressingoperation. In this case, two pressure plates are permanently orremovably mounted side by side on the working surface of the plow spacedinwardly from the runners and meet along the longitudinal nose. Thesepressure plates are inclined outwardly from the plow working surface ina direction towards the end of the plow where the longitudinal surfaceof the runners start at said working surface. In other words, theincline of these plates is opposite to the incline of the outerlongitudinal surface of the runners.

When the tool is constructed for wall joints, it is the same as theabove excepting that the blades are arranged in a very shallow V, andthis V is oposite that of the corner travel. In other words, the workingsurface is on the inside of the V instead of on the outside thereof.

Examples of this invention are illustrated in the accompanying drawings,in which:

FIGURE 1 is an isometric view of a joint trowel for corners,

FIGURE 2 is a plan view of the trowel,

FIGURE 3 is a horizontal section taken on the line 33 of FIGURE 1,

FIGURE 4 is a vertical section taken on the line 4-4 of FIGURE 1,

FIGURE 5 is a diagrammatic horizontal section through a corner showing atape placed over mastic in the corner and before being pressedthereinto,

FIGURE 6 is a diagrammatic plan view of the trowel in the corner andpressing the tape into its final position,

FIGURE 7 is a view similar to FIGURE 6, but with the pressure platesomitted,

FIGURE 8 is a horizontal section through the corner and trowel at thetrailing edge of the latter, illustrating the manner in which the toolspreads the mastic over the tape,

FIGURE 9 is a reduced fragmentary view similar to FIGURE 1, illustratingan alternative form of corner trowel, and

FIGURE 10 is a sectional view similar to FIGURE 3 through a trowel forwall joints, and diagrammatically illustrating the wall joint, saidtrowel being spaced outwardly from the wall.

Referring to the drawings, 10 is a corner joint trowel in the form of aplow 11 having a V-shaped outer working surface 12. As the surface ofthe plow opposite the working surface 12 has nothing to do with theoperation of this tool, said plow may be constructed in any desiredmanner. However, for ease of manufacture and lightness of weight, it ispreferable to form the plow of a pair of blades 15 and 16 angularlyarranged relative to each other and joined together along adjacentlongitudinal edges to form a longitudinal nose 19 along the apex of theV of working surface 12. Actually, blades 15 and 16 may be formed of asingle piece of suitable material, such as metal, plastic or the like,bent along nose 19 to form the outer V-shaped working surface 12. Theangle of blades 15 and 16 relative to each other is a little greaterthan the angle of the corner for which the trowel is designed. Forexample, if the corner angle is 90, the angle of the blades is a littlegreater, such as 100".

Trowel when in operation is moved in the direction of arrow 22 inFIGURE 1. Thus, for the sake of convenience, the opposite edges of plow11 with respect to the direction of movement of the tool are calledleading edge 24 and trailing edge 25. The angle of blades and 16 withrespect to each other at trailing edge 25 determines the thickness ofthe mastic material left in the corner after trowel 10 has been movedover said material. It is preferable to provide narrow flanges 26 and 27along leading edge 24 of blades 15 and 16, said flange projectingoutwardly over working surface 12 of the plow.

Runners 28 and 29 are mounted on the working surface 12 of blades 15 and16 respectively, extend longitudinally thereof and are spaced laterallyfrom longitudinal nose 19. These runners preferably are substantiallyparallel to each other in a direction extending lonigtudinally of plow11, and they are spaced laterally from nose 19 a distance that is alittle greater than half the Width of a tape of the type used in cornerjoints.

Runner 28 has a longitudinal surface 32 spaced outwardly from its blade15 near leading edge 24, as indicated at 33 in FIGURE 1. This runnersurface slopes inwardly to working surface 12 at 34 near trailing edge25. Similarly, runner 29 has a longitudinal surface 36 spaced outwardlyas indicated at 37 from working surface 12 near leading edge 24. Thisrunner surface slopes inwardly to said working surface at 38. Actually,the runner surfaces 32 and 36 meet working surface 12 at 34 and 38spaced forwardly a little from trailing edge 25. In order to provide acontinuous sloping surface from the forward or leading edges of therunners right back to trailing edge 25, blades 15 and 16 are bevelled atsaid trailing edge at 40 and 41, bevel 41 being clearly seen in FIGURE4. When the runner surface 32 and 36 are placed against verticalsurfaces, working surface 12 of the blades slopes from leading edge 24rearwardly towards said vertical surfaces.

Although surface 32 of runner 28 may be of any desired cross sectionalshape, it should be flat in a longitudinal direction, and it preferablyis flat in a lateral direction to provide a relatively wide bearingsurface as illustrated in the drawings. Surface 36 of runner 29 is thesame shape as surface 32.

Any suitable handle means is provided for trowel 10. In this example, ablock 45 is mounted on the face of blades 15 and 16 opposite workingface 12 thereof and at the point of juncture of said blades. This blockhas a socket 46 therein for receiving a ball 47 mounted on a neck 48projecting from the end of a handle 50. Thus, handle 50 is connected toplow 11 by a universal joint formed by the ball and socket arrangement.

If desired, small wings 54 and 55 may be provided at the outer sideedges of blades 15 and 16 at the trailing edge 25. Wings 54 and 55 haverear edges 57 and 58 which lie in the same transverse planes as runnersurface 32 and blade bevel 40, and runner surface 36 and blade bevel 41.These wings form lateral confining walls outside runners 28 and 29 atthe rearward or trailing end of plow 11. It is desirable to provideholes 59 and 60 in blades 15 and 16 respectively between runner 28 andwing 54, and runner 29 and wing 55.

The tool 10 described so far may be used on its own as a finishing tool.However, it may be provided with means for converting it for use in thepreliminary operation of tape pressing, such means being movably orpermanently attached to plow 11, a permanent attachment beingillustrated in the drawings.

A pair of pressure plates 62 and 63 are mounted side by side on workingsurface 12 of the plow spaced inwardly from runners 28 and 29respectively. Plates 62 and 63 are located at and on opposite sides oflongitudinal nose 19 so that they slope away from each other in the samemanner as blade 15 slopes away from blade 16. Although the pressureplates may be independent of each other, it is desirable to connect themalong adjacent edges as at 64 immediately over nose 19. Plates 62 and 63are inclined outwardly from working surface 12 of their respectiveblades 15 and 16 in a direction towards the trailing edge 25 thereof. Itis preferable that these plates be resiliently retained in their normalinclined positions so that they are depressible towards the workingsurface of the plow.

It is preferable to form plates 62 and 63 from a single piece ofsuitable material, such as metal or plastic, as clearly shown in FIGURES1 and 2. This piece of material includes flat portions 66 and 67 whichare secured to the working surface of blades 15 and 16 in any desiredmanner, such as by welding. Plates 62 and 63 extend away and outwardlyfrom flat portions 66 and 67 in the direction of trailing edge 25. Theresiliency of the material from which the plates are formed retains themin their normal positions but permits them to be depressed towardsworking surface 12. In order not to interfere with this depressingaction, a slot 69 is formed in the piece of material between plates 62and 63 extending forwardly from their respective trailing edges 71 and72. It should be noted that the angular relationship of the trailingedges 71 and 72 is opposite to the angular relationship of the trailingedge 25 of the blades 15 and 16. It is preferable to provide one or moreholes 73 in plate 62 and one or 7 more holes 74 in plate 63.

FIGURES 5 to 8 diagrammatically illustrate the action of tool 10 in acorner. The thicknesses of the various materials involved areexaggerated for the sake of clarity. In these figures, and 81 are wallpanels extending substantially at right angles to each other to form acorner joint 82. A layer of mastic material 83 is spread over theadjacent surfaces of walls 80 and 81 and into joint 82, and the tape 86is placed over the mastic and into the corner, as shown in FIGURE 5.

When a corner trowel including pressure plates 62 and 63 is pressed intothe corner, it is moved along said corner, usually from the bottom ofthe walls to the top thereof in a vertical corner, and the trailingedges of plates 62 and 63 resiliently press against tape 86 to force itfirmly into the corner over mastic 83, see FIGURE 6. The angularrelationship of the trailing edges 71 and 72 of the plates 62 and 63exerts a stretching action on the tape outwardly from the corner andmaintains the tape in a taut, unwrinkled condition as the trailing edges71 and 72 pass thereover. As the trowel is moved along the corner, thetape is firmly pressed into position, and this forces excess mastic outfrom the edges of the tape. Runners 28 and 29 being close to said edgesconfine this excess material so that it cannot spread laterally frombeneath the trowel. It will be noted that the pressure plates move overthe tape immediately ahead of the trailing edge 25 of plow 11. Thistrailing edge which is diagrammatically illustrated in FIGURE 8 pressesthe excess mastic inwardly towards walls 80 and 81. As the materialcannot spread outwardly laterally from beneath the tool because ofrunners 28 and 29, it must spread inwardly over tape 86. Flanges 26 and27 help confine the excess mastic between the tool and the walls so thata pressure builds up in the mastic, and this helps to spread it acrossthe top of the tape. In addition, to this, holes 73 and 74 in thepressure plates allow some of the mastic to pass through said plates onto the outer surface of the tape immediately after it has been firmlypressed into the corner. If there is sufiicient mastic, the tape will becompletely covered and the operation finished in one movement of trowel10- along the corner. If the holes 73 and 74 were not provided in thepressure plate to allow the build-up of mastic in front of the pressureplates to pass through these holes, the build-up of mastic in front ofthe plates would be sufiicient to hold the plates away from the tape andthe required action of the plates to press firmly against the tape wouldbe hindered. It should be understood that the trailing edges 71 and 72of the plates 62 and 63 press against the tape to force it firmly intothe corner and as they pass over the tape they will remove practicallyall of the mastic from the tape. It is the function of the trailing edge25 to then spread a thin layer of mastic over the tape in the finishingoperation. It should be kept in mind that the corner may be a verticalone, as the corner of a room, or it may be a horizontal corner, such asthe corner formed between a ceiling and a wall.

The effective transverse angle of plow 11 is that of trailing edge 25.As this angle is a little larger than the angle of the wall corner, theportion of nose 18 at said trailing edge is spaced outwardly from joint82, but the blades eX- tend laterally right to walls 80 and 81, asclearly shown in FIGURE 8. As the runners do not confine the masticalong the bevel 14 at the trailing edge, said mastic is relatively thickat the centre over joint 82 but tapers laterally to merge into thesurfaces of walls 80 and 81. In other words, the mastic material overthe tape is relatively thick at the centre thereof, and featherslaterally to merge with the wall surfaces. If there happens to be toomuch mastic available, wings 54 and 55 prevent it from spreading too faroutwardly from the corner. Furthermore, mastic trapped inside wings 54and 55' passes through holes 59 and 60 in the blades and drops to thefloor. As the blades slope longitudinally away from the walls, theseholes are spaced outwardly from the walls, and so the mastic passingthrough said holes falls clear of the walls.

Sometimes it is not desirable originally to provide sufficient mastic inthe corner for the entire job, or there accidentally is insuflicientmastic. In this case, the operation of the tool is as described above,but the excess mastic squeezed from beneath the tape will not besufiicient to make a good job of covering it. In this case, after thetape has been pressed by the tool into the corner in the mannerdescribed, an additional amount of mastic is applied to the outersurface of the tape. When this is done, a corner trowel without pressureplates 62 and 63 is fitted into the corner and moved therealong. As theleading edge of plow 11 is spaced outwardly from the wall surfacesforrning the corner by the leading edges of runners 28 and 29, the plowrides over the mastic and gradually applies pressure thereto towards theplow trailing edge. This trailing edge distributes the mastic over thetape and smooths it out in the manner described above and clearly shownin FIGURE 8.

Corner trowel not only quickly and easily distributes and smooths themastic in the corner as desired, but it is so constructed that it has tofit accurately into the corner and travel therealong in a proper coursewithout the necessity of the operator being skilled in this work.Runners 28 and 29 automatically locate the tool properly in the cornerwhen it is pressed into said corner. When the runners bear against thesurfaces of walls 80 and 81, the blades of plow 11 are in their properpositions relative to said corner, and said runners prevent the toolfrom being tipped laterally with respect to the corner. The tool cannotbe moved along the corner if the runners are not properly alignedtherewith, and it cannot be moved other than properly along the cornerafter the runners have been correctly positioned.

FIGURE 9 illustrates a modification of the corner joint trowel for usewhere the bearing surface of the wall on one side of a corner isrelatively narrow so that there is no bearing surface available for oneof the runners of 6 the tool. Trowel 10a of FIGURE 9 is not providedwith pressure plates 62 and 63, and instead it has shoes 94 and 95mounted on and projecting from working surface 12a of blades 15a and 16anear nose 19a, said shoes running longitudinally of the trowel.

Trowel 10a is used when one finished wall forming a corner is too narrowto provide a bearing surface for one of the runners of the tool. In thiscase, either shoe 94 or 95 will bear against the narrow portion of thewall so that the trowel functions as described above. As the tool ismoved along the corner, the shoes thereof move through the mastic overthe tape, but the trailing edge of the tool follows the shoes andspreads the mastic out in the proper manner.

FIGURE 10 diagrammatically illustrates trowel for a wall joint. Thistrowel is the same as those described above, except in that its bladesand 116 are arranged in a very shallow V, and the working surface 112thereof is on the inside of a V instead of the outside thereof as is thecase with the other trowels.

FIGURE 10 includes a wall 120 made up of panels 121 and 122 forming ajoint 123 therebetween. Mastic 128 is placed over and into joint 123,and a tape 129 pressed over this mastic. Trowel 110 is moved along wall120 and over joint 123 so that it functions in the manner describedabove to form a layer of mastic 130 over the tape which tapers outwardlyand merges into the wall panels at 123 and 124. Trowel 110 may or maynot be provided with pressure plates similar to plates 62 and 63 oftrowel 10, and it may have shoes similar to shoes 94 and 95 of trowel10a for use when either of the panels 121 and 122 is too narrow toprovide a bearing for one of the runners of the trowel.

What I claim as my invention is:

1. A joint trowel comprising a pair of blades arranged angularlyrelative to each other and joined together along adjacent longitudinaledges to form a wedge shaped plow, each blade having an outer workingsurface, a pair of runners on and extending longitudinally of theworking surface, such runners being positioned in parallel relationshipone on each side of and spaced laterally from the joint adjacentlongitudinal edges and each having outer longitudinal surfaces at anangle to the outer working surface and to the joined adjacentlongitudinal edges, a pair of pressure plates mounted at one end on theouter Working surfaces between the runners to lie normally at an anglesubstantially opposite to the angular longitudinal surface of therunners and away from the outer working surfaces, such pressure platesbeing depressible under tension toward the working surfaces of the plow.

2. The joint trowel as claimed in claim 1 wherein each pressure plate isformed with openings therethrough to allow material in front of thepressure plates to fall through the openings onto the working surfacesof the plow and wherein the trailing edges of each pressure plate liesat an angle substantially opposite to the trailing edge of the workingsurface to which the pressure plate is attached.

References Cited in the tile of this patent UNITED STATES PATENTS109,073 Streeter Nov. 8, 1870 2,420,062 Ames May 6, 1947 2,594,606 AmesApr. 29, 1952 2,824,443 Ames Feb. 25, 1958 2,889,965 Ames June 9, 19592,934,936 Vernon May 3, 1960 FOREIGN PATENTS 506,231 Canada Oct. 5, 1954

